FHB, or scab, affects wheat, barley, oats, corn, and other grasses.
Fusarium graminearum (syn. Gibberella zeae) is favored by warm, humid conditions during flowering and early kernel development.
In addition to yield losses, this fungus produces mycotoxins such as deoxynivalenol (DON) that can accumulate in grain.

Identification

FHB symptoms include bleached spikelets (Fig 1A) first visible 18-21 days after flowering.
Spores may be visible on infected spikelets as pink or orange spore masses (Fig 1B).
Infected grains may shrink and wrinkle, producing tombstone-like kernels which can be pink, gray, and light brown (Fig 2).

Fig 1: Symptoms of FHB. Bleached spikelet; Orange sporulation on symptomatic head

Fig 1: Symptoms of FHB. 1A) Bleached spikelet; 1B) Orange sporulation on symptomatic head

Fig 2: Healthy kernels (left) and “tombstone” Fusarium damaged kernels (right)

Fig 3: Feekes 10.3, Anthesis, Feekes 10.5.1 (yellow anthers beginning flowering), 4 days after anthesis (white anthers post flowering)

Fig 3: From left to right Feekes 10.3, Anthesis, Feekes 10.5.1 (yellow anthers beginning flowering), 4 days after anthesis (white anthers post flowering)

Management

Spikelets are most susceptible at early flowering (Feekes 10.5.1) when anthers emerge. Weather conditions leading up to and following anthesis greatly impact disease development.
Monitor risk at wheatscab.psu.edu.
An integrated management approach is best.
Moderately resistant wheat varieties are available.
Corn is the most common rotation partner of small grains in the region and a host of F. graminearum. Minimizing corn or wheat residues and rotating to a non-host crop when possible, helps to reduce pathogen survival over winter.
Fungicides are most effective in reducing FHB and DON when applied at anthesis (Feekes 10.5.1) but may be applied up to 7 days after flowering (Fig 3).

References

Crop Protection Network (2022, January 28). Fusarium Head Blight of Wheat. Retrieved from: https://cropprotectionnetwork.org/ encyclopedia/fusarium-head-blight- of- wheat

Authors: Joseph Cinderella and Dr. Alyssa Koehler

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